One device of the above kind is described in published French patent specification No. FR 2 633 353A. In that document, the required coupling is achieved using a coupling device which comprises a coupling member and a connecting piece. The coupling member includes a collar portion through which the coupling member is engaged on the diaphragm itself, on the side of the latter opposite to the declutching member. The coupling member also includes a sleeve portion which is adapted to extend through the central opening in the diaphragm. The connecting piece is made of round wire and has a main portion in the form of a ring, which is disposed within the sleeve portion and which is made so as to be deformable resiliently in the radial direction.
The connecting piece is arranged to be attached to the declutching member by means of a simple snap fit of the latter, and also includes at least two toe portions for retaining it on the coupling member. Each of these toe portions includes a radial portion extending in the plane of the main portion of the connecting piece. Each of the toe portions extends individually and locally through the sleeve portion of the coupling member, via openings which are provided in the latter for this purpose. A retaining member is carried axially on the coupling member, either directly or indirectly. This retaining member is provided for the purpose of retaining the connecting piece on the side of the collar portion of the coupling member which lies opposite to the declutching member. For ensuring that the connecting piece remains centred on the coupling member, each toe portion also has an axial portion which extends into the immediate vicinity of the outer periphery of the sleeve portion. Such axial portions complicate the manufacture of the connecting piece.
Two of the toe portions are defined by a local deformation of the connecting piece such that the axial portions necessitate bending in an axial direction, which itself complicates the manufacture of such toe portions.